3-dimensional printed parts

ABSTRACT

The present disclosure is drawn to 3-dimensional printed parts that can include a conductive composite portion and an insulating portion. The conductive composite portion can include a matrix of fused thermoplastic polymer particles interlocked with a matrix of sintered elemental transition metal particles. The insulating portion can include a matrix of fused thermoplastic polymer particles that are continuous with the matrix of fused thermoplastic polymer particles in the conductive composite portion. The insulating portion can be substantially free of sintered elemental transition metal particles and can include transition metal oxide bronze particles.

The present application is a divisional of U.S. patent application Ser.No. 16/325,243 filed on Feb. 13, 2019, which is a National Stageapplication of International Application No. PCT/US2016/058595 filed onOct. 25, 2016, each of which is incorporated herein by reference.

BACKGROUND

Methods of 3-dimensional (3D) digital printing, a type of additivemanufacturing, have continued to be developed over the last few decades.Various methods for 3D printing have been developed, includingheat-assisted extrusion, selective laser sintering, photolithography, aswell as others. In selective laser sintering, for example, a powder bedis exposed to point heat from a laser to melt the powder wherever theobject is to be formed. This allows for manufacturing complex parts thatare difficult to manufacture using traditional methods. However, systemsfor 3D printing have historically been very expensive, though thoseexpenses have been coming down to more affordable levels recently. Ingeneral, 3D printing technology improves the product development cycleby allowing rapid creation of prototype models for reviewing andtesting. Unfortunately, the concept has been somewhat limited withrespect to commercial production capabilities because the range ofmaterials used in 3D printing is likewise limited. Therefore, researchcontinues in the field of new techniques and materials for 3D printing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a 3-dimensional printing system inaccordance with examples of the present disclosure;

FIG. 2 is a close-up side cross-sectional view of a layer ofthermoplastic polymer powder with a conductive fusing agent compositionprinted on a portion of the layer in accordance with examples of thepresent disclosure;

FIG. 3 is a close-up side cross-sectional view of the layer of FIG. 2after the layer has been cured in accordance with examples of thepresent disclosure; and

FIG. 4 is a top plan view of a 3-dimensional printed part having twoelectrically conductive traces in accordance with examples of thepresent disclosure.

The figures depict several examples of the presently disclosedtechnology. However, it should be understood that the present technologyis not limited to the examples depicted.

DETAILED DESCRIPTION

The present disclosure is drawn to the area of 3-dimensional printing.More specifically, the present disclosure provides material sets andsystems for printing 3-dimensional parts with electrically conductivefeatures. In an exemplary printing process, a thin layer of polymerpowder is spread on a bed to form a powder bed. A printing head, such asan fluid jet print head, is then used to print a fusing agentcomposition over portions of the powder bed corresponding to a thinlayer of the three dimensional object to be formed. Then the bed isexposed to a light source, e.g., typically the entire bed. The fusingagent composition absorbs more energy from the light than the unprintedpowder. The absorbed light energy is converted to thermal energy,causing the printed portions of the powder to melt and coalesce. Thisforms a solid layer. After the first layer is formed, a new thin layerof polymer powder is spread over the powder bed and the process isrepeated to form additional layers until a complete 3-dimensional partis printed. Such 3-dimensional printing processes can achieve fastthroughput with good accuracy.

In some examples of the presently disclosed technology, an electricallyconductive fusing agent composition can be used together with anonconductive fusing agent composition to form 3-dimensional printedparts with electrically conductive features. The conductive fusing agentcomposition can be jetted on portions of the powder bed that are desiredto be conductive, and the nonconductive fusing agent composition can bejetting on other portions of the powder bed to form the other portionsof the final printed part. The materials, systems, and methods describedherein can be used to print parts having a wide variety of electricalconfigurations, such as embedded electrical elements and surfaceelectrical elements. The present technology can also make it possible toform electrical elements enabled by 3-dimensional printing that are notpossible using standard electronics manufacturing techniques, such asembedded coils, diagonal vias, and so on.

Although a variety of fusing agent compositions may be effective toabsorb energy to heat and fuse the polymer powder, only certain fusingagent compositions can be effectively used as conductive fusing agentcompositions or nonconductive fusing agent compositions as describedherein. For example, conductive fusing agent compositions can includeconductive materials that, when applied to the polymer powder and thenfused, form a conductive composite material with the fused polymer. Incontrast, the nonconductive fusing agent compositions can form areas inthe 3-dimensional printed part that have very low electricalconductivity. In other words, the nonconductive fusing agentcompositions can form electrically insulating portions in the3-dimensional printed part. These insulating portions can preventcurrent leakage and cross talk between conductive portions of the3-dimensional printed part. Many electronic applications can benefitfrom having multiple conductive elements that are isolated from oneanother by electrically insulating areas.

Carbon black can be used as an energy absorber in fusing agentcompositions, because carbon black can absorb a wide range ofwavelengths of electromagnetic radiation. However, in many cases whencarbon black is used in fusing agent compositions at high enoughconcentrations to be an effective energy absorber, the resulting fusedmaterial will have a significant electrical conductivity. This is likelydue to the fact that carbon black is electrically conductive and has alow inter-particle resistance between particles of the carbon black inthe fused material. Therefore, in some examples of the presenttechnology, particulate energy absorbers with high inter-particleresistance can be used in the nonconductive fusing agent compositions.In particular, transition metal oxide bronzes in particulate form canhave high inter-particle resistances. When such transition metal oxidebronzes are used in fusing agent compositions to form a 3-dimensionalprinted part, the resulting part can be insulating.

As used herein, “insulating” and “nonconductive” can refer to materialsthat have no measurable electrical conductivity or that have extremelylow electrical conductivity compared to the conductivity of3-dimensional printed parts formed using the conductive fusing agentcompositions described herein. In some examples, an insulating portionof a 3-dimensional printed part can have a resistivity of 1,000,000 Ω·mor more.

In one example of the present technology, a material set can include athermoplastic polymer powder having an average particle size from 20 μmto 200 μm; a conductive fusing agent composition including a transitionmetal; and a nonconductive fusing agent composition including transitionmetal oxide bronze particles. In certain examples, the transition metalcan be in the form of elemental transition metal particles. Theelemental transition metal particles can include silver particles,copper particles, gold particles, or combinations thereof. In somecases, the elemental transition metal particles can have an averageparticle size from 10 nm to 200 nm. In further examples, the transitionmetal oxide bronze particles can include a tungsten bronze, a molybdenumbronze, or combinations thereof. In a particular example, the transitionmetal oxide bronze particles can include a cesium tungsten bronze withcomposition Cs_(x)WO₃ (0<x<1) having an average particle size of 2 nm to200 nm. In another example, the transition metal oxide bronze particlescan be in an aqueous dispersion. In further examples, when thenonconductive fusing agent composition is printed between two portionsof the thermoplastic polymer powder printed with the conductive fusingagent composition and the thermoplastic polymer powder is fused byapplying electromagnetic radiation, the nonconductive fusing agentcomposition can substantially prevent crosstalk between conductivecomposite portions formed from the portions printed with the conductivefusing agent composition.

In another example of the present technology, a 3-dimensional printingsystem can include a powder bed including a thermoplastic polymer powderhaving an average particle size from 20 μm to 200 μm, a fluid jetprinter, and a fusing lamp. The fluid jet printer can include a firstfluid jet printing slot in communication with a reservoir of aconductive fusing agent composition to print the conductive fusing agentcomposition onto the powder bed, wherein the conductive fusing agentcomposition includes a transition metal, and a second fluid jet printingslot in communication with a reservoir of a nonconductive fusing agentcomposition to print the nonconductive fusing agent composition onto thepowder bed, and wherein the nonconductive fusing agent compositionincludes transition metal oxide bronze particles. The fusing lamp can beto expose the powder bed to electromagnetic radiation sufficient to fusethermoplastic polymer powder that has been printed with the conductivefusing agent composition or the nonconductive fusing agent composition.In further examples, the transition metal can be in the form ofelemental transition metal particles. In some examples, the elementaltransition metal particles can have an average particle size from 10 nmto 200 nm. In still further examples, the transition metal oxide bronzeparticles can include a tungsten bronze, a molybdenum bronze, orcombinations thereof. In a particular example, the transition metaloxide bronze particles can include a cesium tungsten bronze withcomposition Cs_(x)WO₃ (0<x<1) having an average particle size of 2 nm to200 nm.

In another example of the present technology, a 3-dimensional printedpart can include a conductive composite portion including a matrix offused thermoplastic polymer particles interlocked with a matrix ofsintered elemental transition metal particles; and an insulating portionincluding a matrix of fused thermoplastic polymer particles that iscontinuous with the matrix of fused thermoplastic polymer particles inthe conductive composite portion. The insulating portion can besubstantially free of sintered elemental transition metal particles, andthe insulating portion includes transition metal oxide bronze particles.In a specific example, the transition metal oxide bronze particles caninclude a cesium tungsten bronze with composition Cs_(x)WO₃ (0<x<1)having an average particle size of 2 nm to 200 nm.

In accordance with these examples, the material set, such as for3-dimensional printing, can include a thermoplastic polymer powder, aconductive fusing agent composition, and a nonconductive fusing agentcomposition. The thermoplastic polymer powder can include powderparticles with an average particle size from 20 μm to 200 μm. As usedherein, “average” with respect to properties of particles refers to anumber average unless otherwise specified. Accordingly, “averageparticle size” refers to a number average particle size. Additionally,“particle size” refers to the diameter of spherical particles, or to thelongest dimension of non-spherical particles.

In certain examples, the polymer particles can have a variety of shapes,such as substantially spherical particles or irregularly-shapedparticles. In some examples, the polymer powder can be capable of beingformed into 3D printed parts with a resolution of 20 μm to 200 μm. Asused herein, “resolution” refers to the size of the smallest featurethat can be formed on a 3D printed part. The polymer powder can formlayers from about 20 μm to about 200 μm thick, allowing the fused layersof the printed part to have roughly the same thickness. This can providea resolution in the z-axis direction of about 20 μm to about 200 μm. Thepolymer powder can also have a sufficiently small particle size andsufficiently regular particle shape to provide about 20 μm to about 200μm resolution along the x-axis and y-axis.

In some examples, the thermoplastic polymer powder can be colorless. Forexample, the polymer powder can have a white, translucent, ortransparent appearance. When used with a colorless fusing agentcomposition, such polymer powders can provide a printed part that iswhite, translucent, or transparent. In other examples, the polymerpowder can be colored for producing colored parts. In still otherexamples, when the polymer powder is white, translucent, or transparent,color can be imparted to the part by the fusing agent composition oranother colored ink.

The thermoplastic polymer powder can have a melting or softening pointfrom about 70° C. to about 350° C. In further examples, the polymer canhave a melting or softening point from about 150° C. to about 200° C. Avariety of thermoplastic polymers with melting points or softeningpoints in these ranges can be used. For example, the polymer powder canbe selected from the group consisting of nylon 6 powder, nylon 9 powder,nylon 11 powder, nylon 12 powder, nylon 66 powder, nylon 612 powder,polyethylene powder, thermoplastic polyurethane powder, polypropylenepowder, polyester powder, polycarbonate powder, polyether ketone powder,polyacrylate powder, polystyrene powder, and mixtures thereof. In aspecific example, the polymer powder can be nylon 12, which can have amelting point from about 175° C. to about 200° C. In another specificexample, the polymer powder can be thermoplastic polyurethane.

The thermoplastic polymer particles can also in some cases be blendedwith a filler. The filler can include inorganic particles such asalumina, silica, or combinations thereof. When the thermoplastic polymerparticles fuse together, the filler particles can become embedded in thepolymer, forming a composite material. In some examples, the filler caninclude a free-flow agent, anti-caking agent, or the like. Such agentscan prevent packing of the powder particles, coat the powder particlesand smooth edges to reduce inter-particle friction, and/or absorbmoisture. In some examples, a weight ratio of thermoplastic polymerparticles to filler particles can be from 10:1 to 1:2 or from 5:1 to1:1.

The material set can also include a conductive fusing agent composition.The conductive fusing agent composition can include a transition metal.When the conductive fusing agent composition is printed onto a layer ofthe thermoplastic polymer powder, the conductive fusing agentcomposition can penetrate into the spaces between powder particles. Thelayer can then be cured by exposing the layer to electromagneticradiation. The conductive fusing agent composition can facilitate fusingof the powder particles by absorbing energy from the electromagneticradiation and converting the energy to heat. This raises the temperatureof the powder above the melting or softening point of the thermoplasticpolymer. Additionally, during printing, curing, or both, the transitionmetal in the conductive fusing agent composition can form a conductivetransition metal matrix that becomes interlocked with the fusedthermoplastic polymer particles.

In some examples, the transition metal in the conductive fusing agentcomposition can be in the form of elemental transition metal particles.The elemental transition metal particles can include, for example,silver particles, copper particles, gold particles, platinum particles,palladium particles, chromium particles, nickel particles, zincparticles, or combinations thereof. The particles can also includealloys of more than one transition metal, such as Au—Ag, Ag—Cu, Ag—Ni,Au—Cu, Au—Ni, Au—Ag—Cu, or Au—Ag—Pd.

In certain examples, other non-transition metals can be included inaddition to the transition metal. The non-transition metals can includelead, tin, bismuth, indium, gallium, and others. In some examples,soldering alloys can be included. The soldering alloys can includealloys of lead, tin, bismuth, indium, zinc, gallium, silver, copper, invarious combinations. In certain examples, such soldering alloys can beprinted in locations that are to be used as soldering connections forprinted electrical components. The soldering alloys can be formulated tohave low melting temperatures useful for soldering, such as less than230° C.

In certain examples, the elemental transition metal particles can benanoparticles having an average particle size from 10 nm to 200 nm. Inmore specific examples, the elemental transition metal particles canhave an average particle size from 30 nm to 70 nm.

As metal particles are reduced in size, the temperature at which theparticles are capable of being sintered can also be reduced. Therefore,using elemental transition metal nanoparticles in the conductive fusingagent composition can allow the particles to sinter and form aconductive matrix of sintered nanoparticles at relatively lowtemperatures. For example, the elemental transition metal particles inthe conductive fusing agent composition can be capable of being sinteredat or below the temperature reached during curing in the 3-dimensionalprinting process. In a further example, the thermoplastic polymer powderbed can be heated to a preheat temperature during the printing process,and the elemental transition metal particles can be capable of beingsintered at or below the preheat temperature. In still further examples,the elemental transition metal particles can be capable of beingsintered at a temperature from 20° C. to 350° C. As used herein, thetemperature at which the elemental transition metal particles arecapable of being sintered refers to the lowest temperature at which theparticles will become sintered together, forming a conductive matrix ofsintered particles. It is understood that temperatures above this lowesttemperature will also cause the particles to become sintered.

In additional examples of the conductive fusing agent composition, thetransition metal can be in the form of elemental transition metalparticles that are stabilized by a dispersing agent at surfaces of theparticles. The dispersing agent can include ligands that passivate thesurface of the particles. Suitable ligands can include a moiety thatbinds to the transition metal. Examples of such moieties can includesulfonic acid, phosphonic acid, carboxylic acid, dithiocarboxylic acid,phosphonate, sulfonate, thiol, carboxylate, dithiocarboxylate, amine,and others. In some cases, the dispersing agent can contain an alkylgroup having from 3-20 carbon atoms, with one of the above moieties atan end of the alkyl chain. In certain examples, the dispersing agent canbe an alkylamine, alkylthiol, or combinations thereof. In furtherexamples, the dispersing agent can be a polymeric dispersing agent, suchas polyvinylpyrrolidone (PVP), polyvinylalcohol (PVA),polymethylvinylether, poly(acrylic acid) (PAA), nonionic surfactants,polymeric chelating agents, and others. The dispersing agent can bind tothe surfaces of the elemental transition metal particles throughchemical and/or physical attachment. Chemical bonding can include acovalent bond, hydrogen bond, coordination complex bond, ionic bond, orcombinations thereof. Physical attachment can include attachment throughvan der Waal's forces, dipole-dipole interactions, or a combinationthereof.

In further examples, the conductive fusing agent composition can includea transition metal in the form of a metal salt or metal oxide. Undercertain conditions, a transition metal salt or metal oxide in theconductive fusing agent composition can form elemental transition metalparticles in situ after being printed onto the thermoplastic polymerpowder bed. The elemental transition metal particles thus formed canthen be sintered together to form a conductive matrix. In some examples,a reducing agent can be reacted with the metal salt or metal oxide toproduce elemental metal particles. In one example, a reducing agent canbe underprinted onto the powder bed before the conductive fusing agentcomposition. In another example, a reducing agent can be overprintedover the conductive fusing agent composition. In either case, thereducing agent can be reacted with the metal salt or metal oxide to formelemental metal particles before the thermoplastic polymer particlelayer is cured. Suitable reducing agents can include, for example,glucose, fructose, maltose, maltodextrin, trisodium citrate, ascorbicacid, sodium borohydride, ethylene glycol, 1,5-pentanediol,1,2-propylene glycol, and others.

The concentration of transition metal in the conductive fusing agentcomposition can vary. However, higher transition metal concentrationscan tend to provide better conductivity due to a larger amount ofconductive material being deposited on the powder bed. In some examples,the conductive fusing agent composition can contain from about 5 wt % toabout 50 wt % of the transition metal, with respect to the entire weightof the conductive fusing agent composition. In further examples, theconductive fusing agent composition can contain from about 10 wt % toabout 30 wt % of the transition metal, with respect to the entire weightof the conductive fusing agent composition.

In some examples of the material sets according to the presenttechnology, a pretreat agent composition can be used with the conductivefusing agent composition. The pretreat agent composition can include ametal halide salt, such as a salt of lithium, potassium, or sodium withchloride, bromide, or iodide, for example. The metal halide salt canreact with dispersing agents at the surfaces of transition metalparticles to remove the dispersing agents from the particles. This canincrease the sintering between the metal particles and improve theconductivity of the matrix formed of the sintered particles. Thepretreat agent composition can be dispensed onto the powder bed beforethe conductive fusing agent composition. When the conductive fusingagent composition is printed over the pretreat agent composition, thetransition metal particles can come into contact with the metal halidesalt in the pretreat agent composition. In alternate examples, thepolymer powder can be pretreated with a metal halide salt before beingused in the 3-dimensional printing system. When the conductive fusingagent composition is printed onto the powder bed, the transition metalparticles in the conductive fusing agent composition can come intocontact with the metal halide salt already present on the powder.

Material sets in accordance with the present technology can also includea nonconductive fusing agent composition. In some examples, thenonconductive fusing agent composition can be devoid or substantiallydevoid of the transition metal contained in the conductive fusing agentcomposition. The nonconductive fusing agent composition can containtransition metal oxide bronze particles. These particles can be capableof absorbing electromagnetic radiation to produce heat. In someexamples, transition metal oxide bronze particles can act as broadbandabsorbers, absorbing a wide range of wavelengths of electromagneticradiation. The transition metal oxide bronze particles can especiallyabsorb a broad range of wavelengths in the near-infrared spectrum.

In some examples, the transition metal oxide bronze particles can haveparticle surfaces including an insulating oxide layer. This layer canprovide high inter-particle contact resistance between the transitionmetal oxide bronze particles. In still other examples, the particles,when printed onto polymer powder and fused, can provide a fused materialwith a resistivity of 1,000,000 Ω·m or more.

In some cases, transition metal oxide bronzes can be electricallyconductive as bulk materials. However, when in the form of fineparticles these materials can be nonconductive. The particles can havehigh inter-particle resistance, especially when the particles aredispersed in an aqueous or other hydrolyzing dispersion. Without beinglimited to a particular mechanism, the particles may hydrolyze uponcontact with water and form a layer of insulating oxide with dielectricproperties.

In further examples, the transition metal oxide bronze particles caninclude a tungsten bronze or a molybdenum bronze. Tungsten bronzes andmolybdenum bronzes can respectively have the composition Me_(x)WO₃ orMe_(x)MoO₃ where Me is Na, K, Rb, or Cs and 0<x<1. These materials canhave high inter-particle resistance, especially when the particles aredispersed in an aqueous dispersion Thus, even though the tungsten bronzeor molybdenum bronze materials may be electrically conductive as a bulkmaterial, fine particles of these materials can have high inter-particleresistance. In certain examples, the transition metal oxide bronzeparticles can include a cesium tungsten bronze with the compositionCs_(x)WO₃ where 0<x<1.

In an additional example, the nonconductive fusing agent composition caninclude particulate lanthanum hexaboride (LaB₆). In further examples,the nonconductive fusing agent composition can also include other energyabsorbers capable of absorbing electromagnetic radiation to produce heatwhile also providing an insulating 3-dimensional printed final part.

In some examples, the nonconductive fusing agent composition can includecarbon black together with the transition metal oxide bronze particlesdescribed above. The respective concentrations of carbon black and thetransition metal oxide bronze particles can be sufficient that when thenonconductive fusing agent composition is printed onto polymer powderand the polymer powder is fused, the resulting material isnonconductive.

The amount of the transition metal oxide bronze particles in thenonconductive fusing agent composition can vary depending on the type oftransition metal oxide bronze particles. In some examples, theconcentration of transition metal oxide bronze particles in thenonconductive fusing agent composition can be from 0.1 wt % to 20 wt %.In one example, the concentration of transition metal oxide bronzeparticles in the nonconductive fusing agent composition can be from 0.1wt % to 15 wt %. In another example, the concentration can be from 0.1wt % to 8 wt %. In yet another example, the concentration can be from0.5 wt % to 2 wt %. In a particular example, the concentration can befrom 0.5 wt % to 1.2 wt %.

As mentioned above, the transition metal oxide bronze particles can actas an energy absorber in the nonconductive fusing agent composition.Similarly, the transition metal can act as an energy absorber in theconductive fusing agent composition. Energy absorbers can have atemperature boosting capacity sufficient to increase the temperature ofthe polymer powder above the melting or softening point of the polymerpowder. As used herein, “temperature boosting capacity” refers to theability of an energy absorber to convert near-infrared light energy intothermal energy to increase the temperature of the printed polymer powderover and above the temperature of the unprinted portion of the polymerpowder. Typically, the polymer powder particles can be fused togetherwhen the temperature increases to the melting or softening temperatureof the polymer. As used herein, “melting point” refers to thetemperature at which a polymer transitions from a crystalline phase to apliable, amorphous phase. Some polymers do not have a melting point, butrather have a range of temperatures over which the polymers soften. Thisrange can be segregated into a lower softening range, a middle softeningrange and an upper softening range. In the lower and middle softeningranges, the particles can coalesce to form a part while the remainingpolymer powder remains loose. If the upper softening range is used, thewhole powder bed can become a cake. The “softening point,” as usedherein, refers to the temperature at which the polymer particlescoalesce while the remaining powder remains separate and loose. When thefusing agent composition is printed on a portion of the polymer powder,the energy absorber can heat the printed portion to a temperature at orabove the melting or softening point, while the unprinted portions ofthe polymer powder remain below the melting or softening point. Thisallows the formation of a solid 3D printed part, while the loose powdercan be easily separated from the finished printed part.

Although melting point and softening point are often described herein asthe temperatures for coalescing the polymer powder, in some cases thepolymer particles can coalesce together at temperatures slightly belowthe melting point or softening point. Therefore, as used herein “meltingpoint” and “softening point” can include temperatures slightly lower,such as up to about 20° C. lower, than the actual melting point orsoftening point.

In one example, the energy absorber can have a temperature boostingcapacity from about 10° C. to about 70° C. for a polymer with a meltingor softening point from about 100° C. to about 350° C. If the powder bedis at a temperature within about 10° C. to about 70° C. of the meltingor softening point, then such an energy absorber can boost thetemperature of the printed powder up to the melting or softening point,while the unprinted powder remains at a lower temperature. In someexamples, the powder bed can be preheated to a temperature from about10° C. to about 70° C. lower than the melting or softening point of thepolymer. The fusing agent composition can then be printed onto thepowder and the powder bed can be irradiated with a near-infrared lightto coalesce the printed portion of the powder.

In some examples of the material set according to the presenttechnology, the conductive fusing agent composition and thenonconductive fusing agent composition can be balanced so thatthermoplastic polymer powder that is printed with the conductive fusingagent composition and the nonconductive fusing agent composition reachnearly the same temperature when exposed to light during curing. Thetype and amount of energy absorber in the nonconductive fusing agentcomposition can be selected to match the temperature boosting capacityof the transition metal in the conductive fusing agent composition. Thetype and amount of transition metal in the conductive fusing agentcomposition can also be adjusted to match the temperature boostingcapacity of the energy absorber in the nonconductive fusing agentcomposition. Additionally, in some examples the conductive fusing agentcomposition can contain another energy absorber other than thetransition metal. In certain examples, the conductive fusing agentcomposition and the nonconductive fusing agent composition can raise thetemperature of the thermoplastic polymer powder to temperatures within30° C., within 20° C., or within 10° C. of each other during curing.

In further examples, the material set can also include colored inks foradding color to the thermoplastic polymer powder. This can allow forprinting of full-color 3-dimensional parts. In one example, the materialset can include cyan, magenta, yellow, and black inks in addition to theconductive fusing agent composition, nonconductive fusing agentcomposition, and pretreat agent composition if present.

Each of the conductive fusing agent composition, pretreat agentcomposition, nonconductive fusing agent composition, and additionalcolored inks can be formulated for use in a fluid jet printer such as anink jet printer. The transition metal and transition metal oxide bronzeparticles can be stable in a jetting liquid vehicle and the fusing agentcompositions can provide good jetting performance. In some examples, thetransition metal and transition metal oxide bronze particles can bewater-soluble, water-dispersible, organic-soluble, ororganic-dispersible. The transition metal and transition metal oxidebronze particles can also be compatible with the thermoplastic polymerpowder so that jetting the fusing agent compositions onto the polymerpowder provides adequate coverage and penetration of the transitionmetal and transition metal oxide bronze particles into the powder.

Any of the above described fluids can also include a pigment or dyecolorant that imparts a visible color to the fluids. In some examples,the colorant can be present in an amount from 0.5 wt % to 10 wt % in theinks. In one example, the colorant can be present in an amount from 1 wt% to 5 wt %. In another example, the colorant can be present in anamount from 5 wt % to 10 wt %. However, the colorant is optional and insome examples the fluids can include no additional colorant. Thesefluids can be used to print 3D parts that retain the natural color ofthe polymer powder. Additionally, the fluids can include a white pigmentsuch as titanium dioxide that can also impart a white color to the finalprinted part. Other inorganic pigments such as alumina or zinc oxide canalso be used.

In some examples, the colorant can be a dye. The dye may be nonionic,cationic, anionic, or a mixture of nonionic, cationic, and/or anionicdyes. Specific examples of dyes that may be used include, but are notlimited to, Sulforhodamine B, Acid Blue 113, Acid Blue 29, Acid Red 4,Rose Bengal, Acid Yellow 17, Acid Yellow 29, Acid Yellow 42, AcridineYellow G, Acid Yellow 23, Acid Blue 9, Nitro Blue Tetrazolium ChlorideMonohydrate or Nitro BT, Rhodamine 6G, Rhodamine 123, Rhodamine B,Rhodamine B Isocyanate, Safranine O, Azure B, and Azure B Eosinate,which are available from Sigma-Aldrich Chemical Company (St. Louis,Mo.). Examples of anionic, water-soluble dyes include, but are notlimited to, Direct Yellow 132, Direct Blue 199, Magenta 377 (availablefrom Ilford AG, Switzerland), alone or together with Acid Red 52.Examples of water-insoluble dyes include azo, xanthene, methine,polymethine, and anthraquinone dyes. Specific examples ofwater-insoluble dyes include Orasol® Blue GN, Orasol® Pink, and Orasol®Yellow dyes available from Ciba-Geigy Corp. Black dyes may include, butare not limited to, Direct Black 154, Direct Black 168, Fast Black 2,Direct Black 171, Direct Black 19, Acid Black 1, Acid Black 191, MobayBlack SP, and Acid Black 2.

In other examples, the colorant can be a pigment. The pigment can beself-dispersed with a polymer, oligomer, or small molecule; or can bedispersed with a separate dispersant. Suitable pigments include, but arenot limited to, the following pigments available from BASF: Paliogen®)Orange, Heliogen® Blue L 6901F, Heliogen®) Blue NBD 7010, Heliogen® BlueK 7090, Heliogen® Blue L 7101F, Paliogen®) Blue L 6470, Heliogen®) GreenK 8683, and Heliogen® Green L 9140. The following black pigments areavailable from Cabot: Monarch®1400, Monarch® 1300, Monarch®) 1100,Monarch®1000, Monarch®) 900, Monarch®880, Monarch® 800, and Monarch®)700. The following pigments are available from CIBA: Chromophtal®)Yellow 3G, Chromophtal®) Yellow GR, Chromophtal®) Yellow 8G, Igrazin®Yellow 5GT, Igralite® Rubine 4BL, Monastral® Magenta, Monastral®Scarlet, Monastral® Violet R, Monastral® Red B, and Monastral® VioletMaroon B. The following pigments are available from Degussa: Printex® U,Printex® V, Printex®140U, Printex®140V, Color Black FW 200, Color BlackFW 2, Color Black FW 2V, Color Black FW 1, Color Black FW 18, ColorBlack S 160, Color Black S 170, Special Black 6, Special Black 5,Special Black 4A, and Special Black 4. The following pigment isavailable from DuPont: Tipure®) R-101. The following pigments areavailable from Heubach: Dalamar® Yellow YT-858-D and Heucophthal Blue GXBT-583D. The following pigments are available from Clariant: PermanentYellow GR, Permanent Yellow G, Permanent Yellow DHG, Permanent YellowNCG-71, Permanent Yellow GG, Hansa Yellow RA, Hansa Brilliant Yellow5GX-02, Hansa Yellow-X, Novoperm® Yellow HR, Novoperm® Yellow FGL, HansaBrilliant Yellow 10GX, Permanent Yellow G3R-01, Hostaperm® Yellow H4G,Hostaperm® Yellow H3G, Hostaperm® Orange GR, Hostaperm® Scarlet GO, andPermanent Rubine F6B. The following pigments are available from Mobay:Quindo® Magenta, Indofast® Brilliant Scarlet, Quindo® Red R6700, Quindo®Red R6713, and Indofast® Violet. The following pigments are availablefrom Sun Chemical: L74-1357 Yellow, L75-1331 Yellow, and L75-2577Yellow. The following pigments are available from Columbian: Raven®7000, Raven®5750, Raven® 5250, Raven® 5000, and Raven® 3500. Thefollowing pigment is available from Sun Chemical: LHD9303 Black. Anyother pigment and/or dye can be used that is useful in modifying thecolor of the above described fluids and/or ultimately, the printed part.

The colorant can be included in the conductive fusing agent compositionand/or the nonconductive fusing agent composition to impart color to theprinted object when the fusing agent compositions are jetted onto thepowder bed. Optionally, a set of differently colored fusing agentcompositions can be used to print multiple colors. For example, a set offusing agent compositions including any combination of cyan, magenta,yellow (and/or any other colors), colorless, white, and/or black fusingagent compositions can be used to print objects in full color.Alternatively or additionally, a colorless fusing agent composition canbe used in conjunction with a set of colored, non-fusing agentcompositions to impart color. In some examples, a colorless fusing agentcomposition can be used to coalesce the polymer powder and a separateset of colored or black or white inks not containing an energy absorbercan be used to impart color.

The components of the above described fluids can be selected to give thefluids good jetting performance and the ability to color the polymerpowder with good optical density. Besides the transition metals,transition metal oxide bronze particles, colorants and other ingredientsdescribed above, the fluids can also include a liquid vehicle. In someexamples, the liquid vehicle formulation can include water and one ormore co-solvents present in total at from 1 wt % to 50 wt %, dependingon the jetting architecture. Further, one or more non-ionic, cationic,and/or anionic surfactant can optionally be present, ranging from 0.01wt % to 20 wt %. In one example, the surfactant can be present in anamount from 5 wt % to 20 wt %. The liquid vehicle can also includedispersants in an amount from 5 wt % to 20 wt %. The balance of theformulation can be purified water, or other vehicle components such asbiocides, viscosity modifiers, materials for pH adjustment, sequesteringagents, preservatives, and the like. In one example, the liquid vehiclecan be predominantly water. In some examples, a water-dispersible energyabsorber can be used with an aqueous vehicle. Because the energyabsorber is dispersible in water, an organic co-solvent is not necessaryto disperse the energy absorber. Therefore, in some examples the fusingagent compositions can be substantially free of organic solvent.However, in other examples a co-solvent can be used to help disperseother dyes or pigments, improve the jetting properties of the fusingagent compositions, or improve penetration of the fluid into the powderbed. In still further examples, a non-aqueous vehicle can be used withan organic-dispersible energy absorber.

In certain examples, a high boiling point co-solvent can be included inthe fluids. The high boiling point co-solvent can be an organicco-solvent that boils at a temperature higher than the temperature ofthe powder bed during printing. In some examples, the high boiling pointco-solvent can have a boiling point above 250° C. In still furtherexamples, the high boiling point co-solvent can be present in the fluidsat a concentration from about 1 wt % to about 4 wt %.

Classes of co-solvents that can be used can include organic co-solventsincluding aliphatic alcohols, aromatic alcohols, diols, glycol ethers,polyglycol ethers, caprolactams, formamides, acetamides, and long chainalcohols. Examples of such compounds include primary aliphatic alcohols,secondary aliphatic alcohols, 1,2-alcohols, 1,3-alcohols, 1,5-alcohols,ethylene glycol alkyl ethers, propylene glycol alkyl ethers, higherhomologs (C₆-C₁₂) of polyethylene glycol alkyl ethers, N-alkylcaprolactams, unsubstituted caprolactams, both substituted andunsubstituted formamides, both substituted and unsubstituted acetamides,and the like. Specific examples of solvents that can be used include,but are not limited to, 2-pyrrolidinone, N-methylpyrrolidone,2-hydroxyethyl-2-pyrrolidone, 2-methyl-1,3-propanediol, tetraethyleneglycol, 1,6-hexanediol, 1,5-hexanediol and 1,5-pentanediol.

One or more surfactants can also be used, such as alkyl polyethyleneoxides, alkyl phenyl polyethylene oxides, polyethylene oxide blockcopolymers, acetylenic polyethylene oxides, polyethylene oxide(di)esters, polyethylene oxide amines, protonated polyethylene oxideamines, protonated polyethylene oxide amides, dimethicone copolyols,substituted amine oxides, and the like. The amount of surfactant addedto the formulation of this disclosure may range from 0.01 wt % to 20 wt%. Suitable surfactants can include, but are not limited to, liponicesters such as Tergitol™ 15-S-12, Tergitol™ 15-S-7 available from DowChemical Company, LEG-1 and LEG-7; Triton™ X-100; Triton™ X-405available from Dow Chemical Company; and sodium dodecylsulfate.

Consistent with the formulation of this disclosure, various otheradditives can be employed to optimize the properties of the fluids forspecific applications. Examples of these additives are those added toinhibit the growth of harmful microorganisms. These additives may bebiocides, fungicides, and other microbial agents. Examples of suitablemicrobial agents include, but are not limited to, Nuosept® (Nudex,Inc.), Ucarcide™ (Union carbide Corp.), Vancide® (R.T. Vanderbilt Co.),Proxel® (ICI America), and combinations thereof.

Sequestering agents, such as EDTA (ethylene diamine tetra acetic acid),may be included to eliminate the deleterious effects of heavy metalimpurities, and buffer solutions may be used to control the pH of thefluids. From 0.01 wt % to 2 wt %, for example, can be used. Viscositymodifiers and buffers may also be present, as well as other additives tomodify properties of the fluids as desired. Such additives can bepresent at from 0.01 wt % to 20 wt %.

In addition to the material sets described above, the present technologyalso encompasses 3-dimensional printing systems that include thematerial sets. An example of a 3-dimensional printing system 100 isshown in FIG. 1 . The system includes a powder bed 110 including athermoplastic polymer powder 115 having an average particle size from 20μm to 100 μm. In the example shown, the powder bed has a moveable floor120 that allows the powder bed to be lowered after each layer of the3-dimensional part is printed. The 3-dimensional part can include aconductive portion 125 and an insulating portion 127. The system alsoincludes a fluid jet printer 130 that includes a first printing slot 135in communication with a reservoir of a conductive fusing agentcomposition 140. The first printing slot can be configured to print theconductive fusing agent composition onto the powder bed. A secondprinting slot 145 is in communication with a reservoir of anonconductive fusing agent composition 150. The second printing slot canbe configured to print the nonconductive fusing agent composition ontothe powder bed. After the fusing agent compositions have been printedonto the powder bed, a fusing lamp 160 can be used to expose the powderbed to electromagnetic radiation sufficient to fuse the powder that hasbeen printed with the fusing agent compositions.

The material set used in the 3-dimensional printing system can includeany of the components and ingredients described above. In a particularexample, the conductive fusing agent composition can include elementaltransition metal particles that are silver particles, copper particles,gold particles, or combinations thereof. In a further example, theelemental transition metal particles can have an average particle sizefrom 10 nm to 200 nm. In another example, the transition metal oxidebronze particles in the nonconductive fusing agent composition caninclude a tungsten bronze, a molybdenum bronze, or combinations thereof.In certain examples, the transition metal oxide bronze particles caninclude a cesium tungsten bronze with the composition Cs_(x)WO₃ where0<x<1.

In some examples, the 3-dimensional printing system can also include athird printing slot in communication with a reservoir of a pretreatagent composition to print the pretreat agent composition onto thepowder bed. The pretreat agent composition can include an aqueoussolution of a metal halide salt as described above. In further examples,the 3-dimensional printing system can include additional printing slotsfor colored inks as described above.

To achieve good selectivity between the fused and unfused portions ofthe powder bed, the fusing agent compositions can absorb enough energyto boost the temperature of the thermoplastic polymer powder above themelting or softening point of the polymer, while unprinted portions ofthe powder bed remain below the melting or softening point. In someexamples, the 3-dimensional printing system can include preheaters forpreheating the thermoplastic polymer powder to a temperature near themelting or softening point. In one example, the system can include aprint bed heater to heat the print bed during printing. The preheattemperature used can depend on the type of thermoplastic polymer used.In some examples, the print bed heater can heat the print bed to atemperature from 130° C. to 160° C. The system can also include a supplybed, where polymer particles are stored before being spread in a layeronto the print bed. The supply bed can have a supply bed heater. In someexamples, the supply bed heater can heat the supply bed to a temperaturefrom 90° C. to 140° C.

Suitable fusing lamps for use in the 3-dimensional printing system caninclude commercially available infrared lamps and halogen lamps. Thefusing lamp can be a stationary lamp or a moving lamp. For example, thelamp can be mounted on a track to move horizontally across the powderbed. Such a fusing lamp can make multiple passes over the bed dependingon the amount of exposure needed to coalesce each printed layer. Thefusing lamp can be configured to irradiate the entire powder bed with asubstantially uniform amount of energy. This can selectively coalescethe printed portions with fusing agent compositions leaving theunprinted portions of the polymer powder below the melting or softeningpoint.

In one example, the fusing lamp can be matched with the energy absorbersin the fusing agent compositions so that the fusing lamp emitswavelengths of light that match the peak absorption wavelengths of theenergy absorbers. An energy absorber with a narrow peak at a particularnear-infrared wavelength can be used with a fusing lamp that emits anarrow range of wavelengths at approximately the peak wavelength of theenergy absorber. Similarly, an energy absorber that absorbs a broadrange of near-infrared wavelengths can be used with a fusing lamp thatemits a broad range of wavelengths. Matching the energy absorber and thefusing lamp in this way can increase the efficiency of coalescing thepolymer particles with the energy absorber printed thereon, while theunprinted polymer particles do not absorb as much light and remain at alower temperature.

Depending on the amount of energy absorber present in the polymerpowder, the absorbance of the energy absorber, the preheat temperature,and the melting or softening point of the polymer, an appropriate amountof irradiation can be supplied from the fusing lamp. In some examples,the fusing lamp can irradiate each layer from about 0.5 to about 10seconds per pass.

Other methods of fusing the layers of polymer powder can include usingmicrowave radiation sources, xenon pulse lamps, IR lasers, and othersources of electromagnetic radiation.

The present technology also extends to 3-dimensional printed partsformed from the materials described herein. In one example, a3-dimensional printed part can include a conductive composite portionincluding a matrix of fused thermoplastic polymer particles interlockedwith a matrix of sintered elemental transition metal particles, and aninsulating portion including a matrix of fused thermoplastic polymerparticles that is continuous with the matrix of fused thermoplasticpolymer particles in the conductive composite portion. The insulatingportion can be substantially free of sintered elemental transition metalparticles and can include transition metal oxide bronze particles.

The formation of the conductive composite described above is illustratedin FIGS. 2-3 . FIGS. 2-3 are close-up cross sectional views of a layerof the thermoplastic polymer powder bed that has been printed with aconductive fusing agent composition and a nonconductive fusing agentcomposition. FIG. 2 shows the powder layer 200 after being printed butbefore being cured, and FIG. 3 shows the coalesced powder layer 300after being cured. In FIG. 2 , a first portion 210 of the powder layer200 has been printed with a conductive fusing agent compositioncontaining transition metal particles 220. The transition metalparticles penetrate into the spaces between the powder particles 230. Asecond portion 240 of the powder layer has been printed with anonconductive fusing agent composition including transition metal oxidebronze particles 250. It should be noted that these figures are notnecessarily drawn to scale, and the relative sizes of powder particlesand transition metal particles can differ from those shown. For example,in many cases the transition metal particles can be much smaller thanthe powder particles, such as 2-3 orders of magnitude smaller.

When the powder layer 200 is cured by exposure to electromagneticradiation, the transition metal particles in the first portion 310sinter together to form a matrix of sintered metal particles 320 asshown in FIG. 3 . The thermoplastic polymer particles 230 fuse togetherin the second portion 340, forming a matrix of fused thermoplasticpolymer particles 330. The transition metal oxide bronze particles 250become embedded in the fused polymer in the second portion. The matrixof sintered metal particles and the matrix of fused thermoplasticpolymer particles are interlocked, forming the conductive composite. Itshould be noted that FIG. 3 shows only a 2-dimensional cross-section ofthe conductive composite. Although the sintered metal particles appearto be in isolated locations in the figure, the matrix of sintered metalparticles can be a continuously connected matrix in three dimensions.Thus, the conductive composite can have good electrical conductivitythrough the matrix of sintered transition metal particles.

In some examples, the conductive composite can have sufficientelectrical conductivity to be used to form electrical components. Theresistance of the conductive composite can be tuned in a variety ofways. For example, the resistance can be affected by the type oftransition metal in the conductive fusing agent composition, theconcentration of the transition metal in the conductive fusing agentcomposition, the amount of conductive fusing agent composition dispensedonto the powder bed, the cross section and length of the conductiveportion of the 3-dimensional printed part, and so on. When theconductive fusing agent composition is dispensed by fluid jetting, theamount of conductive fusing agent composition dispensed can be adjustedby changing print speed, drop weight, number of slots from which thefusing agent composition is fired in the fluid jet printer, and numberof passes printed per powder layer. In certain examples, a conductivecomposite element can have a resistance from 1 ohm to 5 Mega ohms. Inone example, the resistance can be measured in the conductive compositeelement over a distance of 1 mm to 1 cm.

Sufficient conductivity can be achieved by dispensing a sufficientamount of the transition metal onto the powder bed. In some examples, asufficient mass of the transition metal per volume of the conductivecomposite can be used to achieve conductivity. For example, the mass oftransition metal per volume of conductive composite can be greater than1 mg/cm³, greater than 10 mg/cm³, greater than 50 mg/cm³, or greaterthan 100 mg/cm³. In a particular example, the mass of transition metalper volume of the conductive composite can be greater than 140 mg/cm³.In further examples, the mass of transition metal per volume ofconductive composite can be from 1 mg/cm³ to 1000 mg/cm³, from 10 mg/cm³to 1000 mg/cm³, from 50 mg/cm³ to 500 mg/cm³, or from 100 mg/cm³ to 500mg/cm³.

In certain examples, a smaller amount of transition metal can bedispensed to achieve surface conductivity, and a larger amount oftransition metal can be applied to achieve bulk conductivity in theconductive composite. Thus, electrical traces can be printed with asmaller amount of transition metal and electrical vias can be printedwith a larger amount of transition metal. As used herein, “trace” refersto an electrically conductive element which conducts electricity alongan x-y plane in the 3-dimensional printed part. The x-y plane refers tothe plane that contains each layer of the powder bed as the layers areprinted. Thus, traces can be oriented along one of the layers that makeup the final 3-dimensional printed part. In various examples, traces canbe on a surface of the final 3-dimensional printed part or embeddedwithin the part. In some examples, traces can be formed with a mass oftransition metal per volume of conductive composite that is greater than1 mg/cm³ or greater than 10 mg/cm³. In further examples, traces can beformed with a mass of transition metal per volume of conductivecomposite from 1 mg/cm³ to 1000 mg/cm³, 10 mg/cm³ to 500 mg/cm³, or 30mg/cm³ to 200 mg/cm³.

As used herein, “via” refers to an electrical element that conductselectricity in the z-axis direction. The z-axis refers to the axisorthogonal to the x-y plane. For example, in 3-dimensional printingsystems having a powder bed floor that lowers after each layer isprinted, the z-axis is the direction in which the floor is lowered. Viascan be formed vertically so that that they conduct electricity in onlythe z-axis direction. Alternatively, vias can be formed in a diagonaldirection that includes components of the z-axis direction and the x-and/or y-axis directions. In some examples, vias can be formed with amass of transition metal per volume of conductive composite that isgreater than 50 mg/cm³ or greater than 100 mg/cm³. In further examples,vias can be formed with a mass of transition metal per volume ofconductive composite from 50 mg/cm³ to 1000 mg/cm³, 100 mg/cm³ to 1000mg/cm³, or 140 mg/cm³ to 500 mg/cm³.

In some examples, the amount of transition metal dispensed onto thepowder bed can be adjusted by printing the conductive fusing agentcomposition in multiple passes. In one example, a single pass of a fluidjet printhead can be sufficient to dispense enough transition metal toachieve surface conductivity. However, in some cases, a single pass isnot sufficient to achieve conductivity in the z-axis direction.Additional passes can be applied to increase the amount of transitionmetal in the transition metal composite. A sufficient number of passescan be used to achieve conductivity in the z-axis direction. In oneexample, three or more passes can be used to form a conductive compositewith conductivity in the z-axis direction. In further examples, theamount of transition metal dispensed can be adjusted by adjusting thedrop weight of the fluid jet printhead either through resistor design orby changing firing parameters. Thus, with a greater drop weight, agreater amount of the conductive fusing agent composition can be printedwith each drop fired. However, in some cases jetting too large an amountof fusing agent composition in a single pass can lead to lower printquality because of spreading. Therefore, in some examples multiplepasses can be used to print more of the conductive fusing agentcomposition with better print quality.

In a particular example, a 3-dimensional printed part can be formed asfollows. A fluid jet printer can be used to print a first pass includingprinting a conductive fusing agent composition onto a first portion ofthe powder bed and printing a nonconductive fusing agent compositiononto a second portion of the powder bed. A curing pass can then beperformed by passing a fusing lamp over the powder bed to fuse thepolymer particles and sinter transition metal particles in theconductive fusing agent composition. Then, one or more additional passescan be performed of printing the conductive fusing agent compositiononto the first portion of the powder bed to increase the amount oftransition metal. Each pass of printing the conductive fusing agentcomposition can be followed by a curing pass with the fusing lamp.Alternatively, a number of passes printing the conductive fusing agentcomposition onto the powder bed can be performed without fusing the bedbetween passes. This can allow the conductive fusing agent compositionto penetrate more fully into the powder bed before the polymer powder isfused. For example, several passes can be performed with the conductivefusing agent composition and then the fusing lamp can be used to fusethe layer. The number of passes used can depend on the desiredconductivity, the contone level of the printing passes (referring to thedensity of fusing agent composition per area deposited on each pass),the type of transition metal in the conductive fusing agent composition,concentration of transition metal in the conductive fusing agentcomposition, thickness of the layer of polymer powder being printed, andso on.

FIG. 4 shows an example of a 3-dimensional printed part 400 includingtwo electrically conductive traces 410. The portions of the printed partmaking up the traces are a conductive composite made by fusing polymerpowder with a conductive fusing agent composition. The remainingportions of the printed part are insulating portions 420. The insulatingportions are made by fusing polymer powder with transition metal oxidebronze particles.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise.

As used herein, “liquid vehicle” or “ink vehicle” refers to a liquidfluid in which additives are placed to form jettable fluids, such asinks. A wide variety of liquid vehicles may be used in accordance withthe technology of the present disclosure. Such liquid or ink vehiclesmay include a mixture of a variety of different agents, including,surfactants, solvents, co-solvents, anti-kogation agents, buffers,biocides, sequestering agents, viscosity modifiers, surface-activeagents, water, etc. Though not part of the liquid vehicle per se, inaddition to the colorants and energy absorbers, the liquid vehicle cancarry solid additives such as polymers, latexes, UV curable materials,plasticizers, salts, etc.

As used herein, “colorant” can include dyes and/or pigments.

As used herein, “dye” refers to compounds or molecules that absorbelectromagnetic radiation or certain wavelengths thereof. Dyes canimpart a visible color to an ink if the dyes absorb wavelengths in thevisible spectrum.

As used herein, “pigment” generally includes pigment colorants, magneticparticles, aluminas, silicas, and/or other ceramics, organo-metallics orother opaque particles, whether or not such particulates impart color.Thus, though the present description primarily exemplifies the use ofpigment colorants, the term “pigment” can be used more generally todescribe not only pigment colorants, but other pigments such asorganometallics, ferrites, ceramics, etc. In one specific aspect,however, the pigment is a pigment colorant.

As used herein, “soluble,” refers to a solubility percentage of morethan 5 wt %.

As used herein, “fluid jetting,” “ink jetting” or “jetting” refers tocompositions that are ejected from jetting architecture, such as ink-jetarchitecture. Ink-jet architecture can include thermal or piezoarchitecture. Additionally, such architecture can be configured to printvarying drop sizes such as less than 10 picoliters, less than 20picoliters, less than 30 picoliters, less than 40 picoliters, less than50 picoliters, etc.

As used herein, the term “substantial” or “substantially” when used inreference to a quantity or amount of a material, or a specificcharacteristic thereof, refers to an amount that is sufficient toprovide an effect that the material or characteristic was intended toprovide. The exact degree of deviation allowable may in some casesdepend on the specific context.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given value may be “alittle above” or “a little below” the endpoint. The degree offlexibility of this term can be dictated by the particular variable anddetermined based on the associated description herein.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to includeindividual numerical values or sub-ranges encompassed within that rangeas if each numerical value and sub-range is explicitly recited. As anillustration, a numerical range of “about 1 wt % to about 5 wt %” shouldbe interpreted to include not only the explicitly recited values ofabout 1 wt % to about 5 wt %, but also include individual values andsub-ranges within the indicated range. Thus, included in this numericalrange are individual values such as 2, 3.5, and 4 and sub-ranges such asfrom 1-3, from 2-4, and from 3-5, etc. This same principle applies toranges reciting only one numerical value. Furthermore, such aninterpretation should apply regardless of the breadth of the range orthe characteristics being described.

EXAMPLES

The following illustrates examples of the present disclosure. However,it is to be understood that the following are only illustrative of theapplication of the principles of the present disclosure. Numerousmodifications and alternative compositions, methods, and systems may bedevised without departing from the spirit and scope of the presentdisclosure. The appended claims are intended to cover such modificationsand arrangements.

Example 1

A 3-dimensional printing system was used to print a part includingmultiple electrically conductive traces separated by insulatingportions. A conductive fusing agent composition, pretreat agentcomposition, and nonconductive fusing agent composition were printedfrom three separate printing slots. The conductive fusing agentcomposition was a silver ink (Mitsubishi NBSIJ-MU01) containing silvernanoparticles. The silver nanoparticles had an average particle size ofapproximately 20 nm. The pretreat agent composition was a solution of 3wt % sodium chloride in water. The nonconductive fusing agentcomposition included cesium tungsten bronze particles in an aqueousvehicle. The cesium tungsten bronze was a non-stoichiometric substancewith the approximate formula Cs_(0.33)WO₃. An additional fusing agentcomposition including carbon black was also tested for comparison.

The tungsten bronze fusing agent composition had the followingformulation: 10.4 wt % 1-(-2-hydroxyethyl)-2-pyrrolidone (HE-2P); 44.44wt % of an aqueous dispersion having 18 wt % of 5 nm tungsten bronzeparticles in the dispersion; 0.62 wt % Tergitol™ 15-S-7 surfactant(available from DOW Chemical Company); and 44.53 wt % water.

The fusing agent compositions and pretreat agent composition were jettedonto a bed of nylon (PA12) particles (Vestosint®×1556). The nylonparticles had an average particle size of approximately 50 μm. The layerthickness was approximately 100 μm. Each layer was printed with thepretreat agent composition followed by the silver ink in the conductiveportions, and the tungsten bronze fusing agent composition or the carbonblack fusing agent composition in the insulating portions. The fluidswere printed at contone levels of 255 for the silver ink, 255 for thepretreat agent composition, and 80 for the tungsten bronze fusing agentcomposition and carbon black fusing agent composition. A single pass ofsilver ink was printed per layer. Using these settings, the amount ofsolid silver dispensed onto the powder was 47 mg/cm³ of the powder layerand the amount of chloride salt dispensed was 7.7 mg/cm³ of the powderlayer.

The printer powder supply and powder bed were filled with the nylonparticles. The supply temperature was set at 110° C. and the print bedtemperature was set at 130° C. A heater under the print bed was set at150° C. The print speed was set at 10 inches per second (ips) and thecure speed was set at 7 ips. Curing was performed using two 300 W bulbsplaced approximately 1 cm away from the surface of the powder bed.

The resistances of the insulating portions of each printed part weremeasured by placing digital multimeter contacts at locationsapproximately 1 cm apart on the surface of the insulating portions. Theinsulating portion formed using the tungsten bronze fusing agentcomposition registered as open, e.g., no measurable electricalconnection between the multimeter contacts was found. The part formedusing the carbon black fusing agent composition measured a resistance of19.06 MΩ. Although this is a rather high resistance, the electricalconductivity of the carbon black can potentially cause cross talkbetween the electrically conductive traces.

Example 2

A nonconductive fusing agent composition is prepared from the followingingredients: 14 wt % 1-(2-hydroxyethyl)-2-pyrrolidone (HE-2P); 4 wt %Silquest® A-1230 dispersing agent (available from Momentive PerformanceMaterials); 44.44 wt % of an aqueous dispersion having 18 wt % of 5 nmtungsten bronze particles in the dispersion; 0.62 wt % Tergitol™ 15-S-7surfactant (available from DOW Chemical Company); and 36.93 wt % water.The nonconductive fusing agent composition is used in a 3-dimensionalprinting system as described in Example 1.

Example 3

A nonconductive fusing agent composition is prepared from the followingingredients: 12 wt % 2-pyrrolidone; 0.80 wt % Surfynol® 465 surfactant(available from Air Products); 8 wt % betaine monohydrate; 44.44 wt % ofan aqueous dispersion having 18 wt % of 5 nm tungsten bronze particlesin the dispersion; and 34.76 wt % water. The nonconductive fusing agentcomposition is used in a 3-dimensional printing system as described inExample 1.

Example 4

A nonconductive fusing agent composition is prepared from the followingingredients: 12 wt % 2-pyrrolidone; 0.80 wt % Surfynol® 465 surfactant(available from Air Products); 8 wt % beta-alanine; 44.44 of an aqueousdispersion having 18 wt % of 5 nm tungsten bronze particles in thedispersion; and 34.76 wt % water. The nonconductive fusing agentcomposition is used in a 3-dimensional printing system as described inExample 1.

What is claimed is:
 1. A 3-dimensional printed part, comprising: aconductive composite portion comprising a matrix of fused thermoplasticpolymer particles interlocked with a matrix of sintered elementaltransition metal particles; and an insulating portion comprising amatrix of fused thermoplastic polymer particles that is continuous withthe matrix of fused thermoplastic polymer particles in the conductivecomposite portion, wherein the insulating portion is substantially freeof sintered elemental transition metal particles, and wherein theinsulating portion comprises transition metal oxide bronze particles. 2.The 3-dimensional printed part of claim 1, wherein the sinteredelemental transition metal particles comprise silver particles, copperparticles, gold particles, or combinations thereof.
 3. The 3-dimensionalprinted part of claim 1, wherein the sintered elemental transition metalparticles are generated from elemental transition metal particles havingan average particle size from 10 nm-200 nm.
 4. The 3-dimensional printedpart of claim 1, wherein the transition metal oxide bronze particlescomprise a tungsten bronze, a molybdenum bronze, or combinationsthereof.
 5. The 3-dimensional printed part of claim 1, wherein thetransition metal oxide bronze particles comprise a cesium tungstenbronze with a composition Cs_(x)WO₃ (0<x<1) having an average particlesize of 2 nm-200 nm.
 6. The 3-dimensional printed part of claim 1,wherein the conductive composite portion further includes conductivefusing agent composition components introduced to the thermoplasticpolymer particles with elemental transition metal particles to form thesintered elemental transition metal particles.
 7. The 3-dimensionalprinted part of claim 1, wherein the insulating portion further includesnonconductive fusing agent composition components introduced to thethermoplastic polymer particles with the transition metal oxide bronzeparticles.
 8. The 3-dimensional printed part of claim 1, wherein theinsulating portion substantially prevents crosstalk between twoconductive composite portions.
 9. The 3-dimensional printed part ofclaim 1, wherein the conductive composite portion and the insulatingportion are thermally fused.